Recently, extensive efforts have been made in research and development of biometric authentication technology for authentication by a physical feature of the subject in place of codes or passwords consisting of a combination of characters and symbols. In biometric authentication, physical features that are never identical between individuals, such as one's fingerprint, vein pattern on the back of a hand, iris pattern, and vocal print, are usually utilized. Particularly, as authentication apparatuses utilizing fingerprints or vein patterns on the back of one's hand have been improved in the accuracy of authentication and reduced in cost, they are installed in various devices such as ATMs (automatic teller machines) and personal computers (PCs).
However, authentication by the fingerprint or vein pattern on the back of a hand requires the subject to make a part of his/her body, a finger or a hand, contact with the apparatus or place it close to the apparatus to a certain extent. For this reason, recently, authentication by the iris pattern has drawn attention (for example, see Patent Literature 1).